1. Field of the Invention
The present invention relates to the negative type weaving dobbies for the shed forming on weaving looms and it deals more specifically with the fastening of the pulling cables on the suspension levers associated with the heald shafts frames.
2. Brief Description of the Related Art
The object of document EP-A-0 457 696 (STAUBLI) is a fastening system that comprises, on the one hand, a terminal eyelet for each pulling cable of the dobby that is secured to a hollow ferrule of an axial housing for the crimping of the end of said cable and, on the other hand, a bearing pad having at least one longitudinal groove for the purpose of taking up this cable directly behind the eyelet. The pad is designed so as to be held against the terminal edge of the contemplated suspension lever, while each eyelet is secured by a removable pin on the aforementioned edge.
Such a fastening system has been proven satisfactory on a practical plan but its utilization revealed its limitations.
As a matter of fact, the displacement loads and speeds of the pulling cables become greater at all times which entails having to resort to cables with a greater diameter. Well now, the available space on each suspension lever is very reduced because of the slight thickness of these elements, coupled with a limited reciprocal spacing; therefore, it is necessary to provide two eyelets on the same lever for the two cables associated with the same heald shafts frames. Thus, the fastening of these cables on the ferrules of the eyelets becomes very difficult while, at the same time, the reliability of the securing of the eyelets on the flange of the edge of the levers is considerably reduced.
It must be noted that the stresses applied to the cables are irregular and differ from one cable to the next. The removable fastening pin is thus subjected to bending moments that are added to the vibrations resulting from the high operating speeds, with the result that there is a tendency to let the eyelets slip, running the risk that they to get caught by one lever over another one, taking into account the slight spacing of the levers.